Bite-block effects on native s/ʃ and English r/l in child speakers of a language with/without this contrast

Learning to produce non-native speech contrasts requires developing new phonological categories as well as new articulatory-perceptual mappings for these new categories. However, within the same speakers, it remains unclear how these new categories compare to contrasts that are already fully established in the native language. To examine potential differences between native and non-native sounds, we recorded Japanese children’s (8–12 years) productions of a non-native contrast (English /ɹ/−/l/, indexed by F3–F2) and a native contrast (/s/−/ʃ/, indexed by Center of Gravity). Recordings were done both under normal speaking conditions and under articulatory perturbation induced by a temporary bite-block while listening to a model. Children acoustically differentiated both contrasts under normal speaking conditions, but the two contrasts showed different developmental profiles: differentiation of the native contrast did not vary with age, whereas differentiation of the non-native contrast was significant only in older children. As expected, the bite-block manipulation reduced acoustic distinctness for both contrasts; however, susceptibility to this disruption was age-invariant for the native contrast but increased with age for the non-native contrast.